In a wire stranding system, wire is payed off from a plurality of reels to a stranding station. As the wire on a reel is exhausted, the reel must be replaced with one from a fresh supply of wire. The reels are rotatably supported in cradles which are also rotatably mounted. It is common practice to have the reels rotatably mounted on pintles which are fluid actuated to release the reel, while being spring biased into a reel engaging position.
U.S. Pat. No. 4,406,423 discloses a new and improved pintle actuating system of the fluid operated type in which the pintles are actuated to disengage a reel upon application of fluid pressure using a piston-cylinder arrangement.
The invention described in the aforementioned patent further provides an improved and simplified warning and safety device, which until actuated, will not permit retraction of the piston and the pintle therewith; and, further provides means for always signifying when the pintle is not in a full engaging position with the reel. A pintle actuating device may generally be considered as a spring biased device for engaging a reel and a fluid actuated retract system.
In the present invention, substantial clearance may be left between the piston and cylinder walls and an annular diaphragm is provided overlying a wall of the piston and the cylinder defining means, and defining a seal therebetween. Then, when fluid pressure is applied to the piston, there need be no sealing engagement or close contact between the piston and cylinder inasmuch as the diaphragm provides a seal and will in essence roll with movement of the piston in the cylinder, in the clearance therebetween. One or more guide pins may be provided for maintaining the axial position of the piston and the cylinder. The piston itself rotatably carries the pintle which engages the reel. Radially extending through the cylinder defining means is a retaining pin which normally closes a fluid passage to the cylinder, and maintains the piston in a given reel engaging position. Before the piston can be retracted to disengage the reel, the pin must be moved, under the influence of fluid pressure, to uncover a passageway into the piston-cylinder assembly. The pin is arranged so that when it is retracted, an indication is given that the pintle is not in a reel engaging position. Upon reactuation of the pintle to again engage a reel, the safety device will alert the operator whenever the pintle is not in a full reel engaging position. However, when the pintle is in the full engaging position, the warning is extinguished.
In practice, it has been found that under unexpected and severe operating conditions where the strand breaks, the cradle may rotate uncontrollably and cause the pintle piston therein to retract and shear a retaining pin. This may cause the reel to lose engagement with the pintle and fly from the pintle. While such situations are rare, adequate means should be provided to guard against the occurrence.